Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1999-06-09
2001-06-12
Weiss, John G. (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S380000, C604S378000, C604S384000
Reexamination Certificate
active
06245961
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an absorbent article, such as a diaper, pant diaper, incontinence guard, sanitary napkin, wound dressing and the like, of the kind comprising a liquid pervious topsheet, a liquid impervious backsheet and an absorbent body arranged therebetween.
BACKGROUND OF THE INVENTION
Absorbent articles of the above mentioned kind are intended for absorption of body fluids, such as urine and blood. As a liquid pervious topsheet which is facing the wearer during use, they usually exhibit a nonwoven material, for example of spunbond-type. It is also previously known to arrange a liquid acquisition layer between the topsheet layer and the absorbent body, said liquid acquisition layer having the ability to quickly receive large quantities of liquid, and to distribute the liquid and temporarily store it before it is absorbed by the underlying absorbent body. This is of great importance, especially in the thin compressed absorbent bodies of today, often comprising a high content of so called superabsorbents, which certainly have a high absorption capacity but in many cases a too low absorption rate in order to instantaneously be able to absorb the large quantity of liquid which can be discharged in a few seconds during urination. A porous, relatively thick acquisition layer, for example in the form of a fibrous wadding, a carded fibrous web, or another type of fibrous material, has a high instantaneous liquid-receiving capacity and is able to store the liquid temporarily until it has been absorbed by the absorbent body. The same applies for porous foam materials. The liquid is thereafter drained successively into the underlying absorbent body, after which the acquisition layer once again has the capacity to receive liquid from a repeated wetting.
Examples of absorbent articles comprising such porous acquisition layers are, for example, disclosed in U.S. Pat. No. 3,371,667, EP-A-0,312,118 and EP-A-0,474,777.
The materials used today as acquisition layers in absorbent articles are mostly functioning well, but are relatively expensive and can sometimes exhibit an insufficient acquisition rate, especially in the second and third wettings, if large quantities of liquid are involved.
It is previously known through EP-A-0,391,814 and GB-B-2,209,672 to use continuous, unbonded synthetic fibres, so-called tow, in absorbent articles for distributing liquid in the longitudinal direction of the article.
Another problem is that conventional liquid pervious topsheet materials used for absorbent articles of this kind, usually a nonwoven material of synthetic fibres, e.g. a spunbond material, often have a lower acquisition rate for liquid than the acquisition layer, wherein liquid can leak out from the article before it reaches the acquisition layer. This problem can of course be solved by using a topsheet material which is very open and therefore has a high liquid permeability. Such an open topsheet material may, however, cause problems with too low strength and sharp fibre ends from the acquisition layer which penetrate the open topsheet material and irritate the user.
OBJECT AND MOST IMPORTANT FEATURES OF THE INVENTION
The object of the present invention is to provide a material which exhibits a high acquisition rate for liquid also in repeated wettings, exhibits a high strength and wear resistance, high comfort, high processability and has a relatively low price. Furthermore, it should be possible to combine different wishes, concerning the function of the material and the absorption properties, in the same material. According to the invention, this has been achieved by means of a layer of continuous fibres, so-called tow, which are bonded in points, lines or spots in a bonding pattern, but otherwise are substantially unbonded to each other, and which layer comprises at least two different zones, as seen in the cross-sectional direction of the layer, which zones are different from each other with respect to one or several properties, such as basis weight, density, pore size, hydrophilicity/hydrophobicity and/or other absorption properties and/or properties affecting skin condition.
Herein, “cross-sectional direction of the layer” means a plane which is transverse to the fibre direction.
According to one embodiment, the layer exhibits different basis weight and/or density in its central portion than in its, in relation to the fibre direction, longitudinal edge portions,
According to another embodiment, the layer comprises at least two different fibre types or fibre grades, which constitute said different zones. Thereby, the different fibre types can exhibit different thickness, fibre cross-section, crimp and/or elasticity modulus. Furthermore, they can be of different polymeric materials and/or exhibit different surface treatments.
The different fibre types can either constitute different layers in the z-direction of the layer, or different zones in the y-direction, or a combination of both.
The different fibre types can constitute different discreet zones in the article, or be partially integrated with each other.
The layer can be used as a liquid acquisition layer underneath a topsheet, as a topsheet material, or as an integrated topsheet/liquid acquisition layer.
Further features of the invention are evident from the following description and from the claims.
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Hansson Roy
Ronnberg Peter
Roxendal Sofia
Burns Doane Swecker & Mathis L.L.P.
Mager Carie
SCA Hygiene Products AB
Weiss John G.
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